A094269 a(n) = phi(A003401(n)).

1, 1, 2, 2, 4, 2, 4, 4, 4, 8, 8, 16, 8, 8, 8, 16, 16, 16, 16, 32, 16, 32, 32, 32, 64, 32, 32, 32, 64, 64, 64, 64, 64, 64, 64, 128, 128, 256, 128, 128, 128, 128, 128, 128, 128, 256, 256, 256, 256, 256, 256, 512, 256, 256, 256, 512, 512, 512, 512, 1024, 512, 512, 512, 512

Offset: 1

Author

Labos Elemer, Jun 02 2004

Keywords

• nonn

Comments

All terms are powers of 2. - Jianing Song, Sep 28 2018

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000010, A003401, A319821.

Programs

Mathematica

Do[If[IntegerQ[Log[2, EulerPhi[n]]], Print[n];ta[[u]]=n;u=u+1], {n, 1, 10000}] EulerPhi[ta]

PARI

for(n=1, 1000, my(i=eulerphi(n)); if(omega(2*i)==1, print1(i, “, “))) \\ Jianing Song, Sep 28 2018

Formula

a(n) = 2^A319821(n). - Amiram Eldar, Sep 25 2024